title: Exposed surfaces on shape-controlled ceria nanoparticles revealed through AC-TEM and water-gas shift reactivity.
abstract: Aberration-corrected transmission electron microscopy and high-angle annular dark field imaging was used to investigate the surface structures and internal defects of CeO2 nanoparticles (octahedra, rods, and cubes). Further, their catalytic reactivity in the water-gas shift (WGS) reaction and the exposed surface sites by using FTIR spectroscopy were tested. Rods and octahedra expose stable (111) surfaces whereas cubes have primarily (100) facets. Rods also had internal voids and surface steps. The exposed planes are consistent with observed reactivity patterns, and the normalized WGS reactivity of octahedra and rods were similar, but the cubes were more reactive. In situ FTIR spectroscopy showed that rods and octahedra exhibit similar spectra for -OH groups and that carbonates and formates formed upon exposure to CO whereas for cubes clear differences were observed. These results provide definitive information on the nature of the exposed surfaces in these CeO2 nanostructures and their influence on the WGS reactivity.
authors.affiliation: Catalytic Processes and Materials, MESA+Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE Enschede (The Netherlands).
authors.forename: Shilpa
authors.initials: S
authors.lastname: Agarwal
authors.forename: Leon
authors.initials: L
authors.lastname: Lefferts
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Mojet
authors.forename: D A J Michel
authors.initials: DA
authors.lastname: Ligthart
authors.forename: Emiel J M
authors.initials: EJ
authors.lastname: Hensen
authors.forename: David R G
authors.initials: DR
authors.lastname: Mitchell
authors.forename: Willem J
authors.initials: WJ
authors.lastname: Erasmus
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Anderson
authors.forename: Ezra J
authors.initials: EJ
authors.lastname: Olivier
authors.forename: Johannes H
authors.initials: JH
authors.lastname: Neethling
authors.forename: Abhaya K
authors.initials: AK
authors.lastname: Datye
mesh_terms: D000327:Adsorption; D002248:Carbon Monoxide / Q000737:chemistry*; D002563:Cerium / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D002563:Cerium; C030583:ceric oxide; D002248:Carbon Monoxide; D006859:Hydrogen
keywords: aberration-corrected TEM; ceria; heterogeneous catalysis; nanoparticles; water-gas shift reaction